diff --git a/misc/vim/syntax/cton.vim b/misc/vim/syntax/cton.vim
index 6ccacae7fc..4862c38ec8 100644
--- a/misc/vim/syntax/cton.vim
+++ b/misc/vim/syntax/cton.vim
@@ -14,7 +14,7 @@ endif
 syn spell notoplevel
 
 syn keyword ctonHeader test isa set
-syn keyword ctonDecl function jump_table incoming_arg outgoing_arg spill_slot local emergency_slot
+syn keyword ctonDecl function jump_table incoming_arg outgoing_arg spill_slot explicit_slot emergency_slot
 syn keyword ctonFilecheck check sameln nextln unordered not regex contained
 
 syn match ctonType  /\<\([bif]\d\+\(x\d\+\)\?\)\|[if]flags\>/